I'm having precisely the same issue. It is sporadic but began with LS302nightly. Wake from sleep yields dark grey screen with visible mouse cursor but no way to interact. Remoting in from another machine also does not work. LS crash log timestamp matches the second I attempted wake from sleep.
*EDIT: btw this does not happen on a 2 machines running 10.7.5 and one running 10.6.8
*EDIT: btw this does not happen on a 2 machines running 10.7.5 and one running 10.6.8